Dear Johsan,

One of my favorite holidays is Pi Day. On March 14, people who love the math constant called pi celebrate by eating the other kind of pie. Like apple pie, pumpkin pie and even pizza pie.

I talked about the number pi with my friend Kristin Lesseig. She studies how kids learn math.

She told me pi is the ratio between the distance around a circle and the distance across a circle. A ratio is the relationship between two numbers. We usually think of pi as about 3.14—but there’s more to it than that.

Dear Thomas,

Every few years, a smell like a rotting corpse wafts around a stairwell at Washington State University Vancouver. But it’s not really a dead body. It’s the bloom of the corpse flower plant.

There are fewer than 1,000 corpse flower plants left in the wild. It’s one of the rarest plants in the world.

But the list of rare plants is massive. If you look at all the plants we know about in the world, there are about 435,000 different kinds of plants—and many more we don’t know about. Some scientists say that more one-third of all plants are “exceedingly rare.”

I … » More …

Dear Liam,

Did you know your skin is the largest organ in your body? The average 5th grader has more than 6 pounds of skin. Whoa.

Skin protects the inside of your body from the dirty outside world. It keeps your insides from drying out and ensures a steady body temperature. It lets you feel things you touch.

Your skin also has the incredible ability to heal itself. I talked about that with my friend Edward Johnson. He teaches classes about the human body in the School of Biological Sciences at Washington State University.

“Skin is the point of contact between you and everything in … » More …

Dear Lara,

Sometimes I get an overwhelming urge to rub my face on things I love—like my microscope. Other times I’m so happy to see my tortoiseshell roommate that we bump our heads together.

I talked about why I do that with my friend Dr. Jessica Bell. She’s a veterinarian at Washington State University.

She told me that cats rub their cheeks on things when they’re happy or want to say that thing belongs to them.

Dear Maite,

People have thought about mermaids for a long time. Ancient people even drew humans with fish tails on cave walls. So, did they really see mermaids or were they drawing from imagination?

The marine experts from the National Oceanic and Atmospheric Administration (NOAA) say that no mermaids have ever been found in the ocean.

But we’ve fully mapped only about one-quarter of the ocean floor. There are probably between 700,000 and one million different kinds of plants and animals in the ocean. At least two-thirds of those are still unknown to us.

Does that mean mermaids could be swimming around in parts … » More …

Dear Alivia,

My neighbor has a very prickly garden. It’s full of cactuses—including one thorny plant nearly as tall as my house. That’s not something you see every day in the Pacific Northwest. Cactuses usually live in dry places like deserts.

I talked about your question with my friend Linda Chalker-Scott. She’s a garden scientist at Washington State University.

Dear Luke and Wade,

When I get the same question from different kids, I know it’s a good one.

So, I talked about your question with my friend Angeliqua Montoya. She’s a graduate student at Washington State University. She works on a mutualism between pea plants and bacteria.

“I study ecology, which is looking at interactions between different species,” she said. “Mutualisms are interactions where both species benefit.”

Dear Mya,

It’s hard to imagine that one space rock wiped out the dinosaurs. But it did more than that. It killed 75% of the plants and animals on Earth. Me-OW.

I talked about that with my friend Barry Walker. He teaches geology classes about Earth’s history at Washington State University.

Walker told me that we call a space rock that hits Earth a meteorite. The meteorite that took out the dinosaurs set off changes on Earth. Those changes lasted for thousands of years. That’s how it killed so many things.

Dear Lamarcus,

My goldfish roommate hates when people tap on his tank. The tapping sound he hears in the water is loud and scary.

I talked with my friend Rikeem Sholes about how fish hear. He’s a fish scientist. He studies salmon hearing at Washington State University.

He told me that a fish’s hearing system includes sensory cells in the inner ear and in a line along the outside of the fish’s body and head. Some fish also use their swim bladder to have super hearing.

Dear Ia,

I looked through a high-power telescope for the first time in college. I couldn’t believe how many stars I saw. It’s hard to imagine all the planets orbiting all those stars.

I talked about how we know those planets are out there with my friend Jose Vazquez. He’s an astronomer at Washington State University.

He told me that scientists look for planets outside our solar system using a number of instruments—like a photometer. That’s a tool that attaches to a telescope and measures light.